The invention pertains to energy recovery systems utilized with refrigeration systems for heating water with refrigerant compressor by-product heat.
In a typical refrigeration circuit such as utilized in refrigeration or air conditioning apparatus, considerable heat is generated during the compression of the system refrigerant, and such heat occurs in the hot gases being compressed. The possibility of utilizing this waste heat has long been recognized. and the prior art discloses a number of arrangements wherein this heat can be recovered for practical use, usually for water heating purposes, and reference is made to U.S. Pat. Nos. 1,331,600; 1,786,861; 2,125,842 and 2,562,651.
One of the problems arising from heat recovery systems which heat water by salvaging heat from a refrigeration compressor circuit is due to the fact that the temperature of the compressor gas is considerably higher than the desired temperature of the heated water. The temperature within the compressor heat exchanger is usually above 200.degree. F., while a desired hot water temperature for commercial and domestic use is usually between 125.degree. and 145.degree.. The majority of hot water storage tanks utilize safety pressure relief valves to prevent the buildup of excessive tank pressure, and such safety valves may open at 200.degree. F. and, further, elevated tank temperatures create a serious safety hazard to hot water users.
Several types of controls have been utilized to prevent excessive water temperatures from occurring within the water storage tank in energy recovery systems used in conjunction with refrigeration apparatus. One such system is disclosed in U.S. Pat. No. 3,922,876 wherein the pump which circulates water through the hot water storage tank and the refrigeration apparatus heat exchanger is controlled by an electric switch sensing the temperature within the water being drawn from the tank, and de-energizes the circulating pump once the circulated water has reached a predetermined temperature. This patent also uses a temperature sensing blocking valve located in close proximity to the heat exchanger in order to prevent water being circulated through the storage tank which is of a temperature considerably below the desired temperature within the storage tank. While the apparatus and control system disclosed in U.S. Pat. No. 3,922,876 prevents excessive water temperatures from developing in the storage tank, and also prevents low temperature water from being introduced into the tank, this apparatus causes the circulating pump to continually cycle, and during continuous refrigeration system operation during low hot water consumption periods the water within the storage tank will be subject to stratification thereby limiting the median water temperature level within the tank. The instant invention constitutes an improvement over U.S. Pat. No. 3,922,876.
In the practice of the invention a diverting valve bypasses the circulated water around the refrigerant compressor heat exchanger upon a predetermined water temperature being achieved, and while the concept of using heat exchanger bypasses has been suggested in the prior art, note U.S. Pat. Nos. 2,700,279 and 3,926,008, such prior art devices have not utilized the economical and simplified system disclosed herein, and the prior art devices are not considered to meet the needs of apparatus of the type disclosed.